I'm 6' tall (just a hair over actually) and weiging in at about 255 +/- 5lbs.

I visited the LBS today and talked to the Owner/Manager who was working there, he didn't have any Cross bikes in stock but said he could order me one. I asked him about sizing and how he'd know what bike would fit, he told me "He just knew, 'cause he'd been doing it so long". He said I'd have no problem on any Roadbike and there were lots of his customers on the ultralight race bikes that were bigger than I am. I told him I'd check back in after I visited a few more shops. He carries Kona/Fuji/Raliegh/Giant and some other lines.